Hi Jon, i'll like to give my thought on this, as to how it can be done:-
1st - knowing the Phone's location, it had to be a proprietary system that tracks either Wifi or Bluetooth; not cell or GPS triangulation though, as the phone may be travelling in mutli-levels enclosure, cell or GPS trianulgulation only give 2D geo-location not 3D. With Wifi, mostly likely, a fingerprinting methodology will has to be applied within an smart phone App, this will also mean a holistic pre-site survey will have to be done at every building or location that needed to track the phone.With Bluetooth, a presence locate methodology will be most likely candidate, this will require a large numbers of proprietary Bluetooth Detection Base Stations to be installed at the location for tracking, the number of base stations required will depends on the tracking granularity required.
2nd - knowing the camera position, similar to above, the camera location can be indexed on a floor plan or map which matches the geo coding of any above positioning technology. Yes, Jon, you are right to say, a manual input for camera location will be to done in this case.
With the phone's location and camera's location known, its just simple geo code (tile or grid) matching to bring up the right camera when the phone move along the "pre-configured tracked space"
If i were to do this, my choice will be Wifi, as it requires no additional hardware on site (provided the site already has abundance of "free" wifi signals), but will require a certain level of technical competency in wireless fingerprinting know-how though.
Like to know if anyone here has any other thought on this?